java.lang.Object
- org.checkerframework.checker.nullness.util.Opt

```
@AnnotatedFor("nullness")
public final class Opt
extends java.lang.Object
```
Utility class providing every method in Optional, but written for possibly-null references rather than for the Optional type.
To avoid the need to write the Opt class name at invocation sites, do:
```
import static org.checkerframework.checker.nullness.util.Opt.orElse;
```
or
```
import static org.checkerframework.checker.nullness.util.Opt.*;
```
Runtime Dependency: If you use this class, you must distribute (or link to) checker-qual.jar, along with your binaries. Or, you can copy this class into your own project.
See Also:

Optional

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method	Description
`static <T> @Nullable T`	`filter(T primary, java.util.function.Predicate<? super @NonNull T> predicate)`	If primary is non-null, and its value matches the given predicate, return the value.
`static <T extends @NonNull java.lang.Object> T`	`get(T primary)`	If primary is non-null, returns it, otherwise throws NoSuchElementException.
`static <T> void`	`ifPresent(T primary, java.util.function.Consumer<? super @NonNull T> consumer)`	If primary is non-null, invoke the specified consumer with the value, otherwise do nothing.
`static boolean`	`isPresent(@Nullable java.lang.Object primary)`	Returns true if primary is non-null, false if primary is null.
`static <T,U> @Nullable U`	`map(T primary, java.util.function.Function<? super @NonNull T,? extends U> mapper)`	If primary is non-null, apply the provided mapping function to it and return the result.
`static <T> @NonNull T`	`orElse(T primary, @NonNull T other)`	Return primary if it is non-null.
`static <T> @NonNull T`	`orElseGet(T primary, java.util.function.Supplier<? extends @NonNull T> other)`	Return `primary` if it is non-null.
`static <T extends @NonNull java.lang.Object,X extends @NonNull java.lang.Throwable> T`	`orElseThrow(T primary, java.util.function.Supplier<? extends X> exceptionSupplier)`	Return primary if it is non-null.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

get
```
public static <T extends @NonNull java.lang.Object> T get(T primary)
```
If primary is non-null, returns it, otherwise throws NoSuchElementException.

Type Parameters:

T - the type of the argument

Parameters:

primary - a non-null value to return

Returns:

primary if it is non-null

Throws:

java.util.NoSuchElementException - if primary is null

See Also:

Optional.get()

isPresent

@EnsuresNonNullIf(expression="#1",
                  result=true)
public static boolean isPresent(@Nullable java.lang.Object primary)

Returns true if primary is non-null, false if primary is null.

See Also:: Optional.isPresent()

ifPresent

public static <T> void ifPresent(T primary,
                                 java.util.function.Consumer<? super @NonNull T> consumer)

If primary is non-null, invoke the specified consumer with the value, otherwise do nothing.

See Also:: Optional.ifPresent(Consumer)

filter
```
public static <T> @Nullable T filter(T primary,
                                     java.util.function.Predicate<? super @NonNull T> predicate)
```
If primary is non-null, and its value matches the given predicate, return the value. If primary is null or its non-null value does not match the predicate, return null.

See Also:

Optional.filter(Predicate)

map

public static <T,U> @Nullable U map(T primary,
                                          java.util.function.Function<? super @NonNull T,? extends U> mapper)

If primary is non-null, apply the provided mapping function to it and return the result. If primary is null, return null.

See Also:: Optional.map(Function)

orElse

public static <T> @NonNull T orElse(T primary,
                                    @NonNull T other)

Return primary if it is non-null. If primary is null, return other.

See Also:: Optional.orElse(Object)

orElseGet

public static <T> @NonNull T orElseGet(T primary,
                                       java.util.function.Supplier<? extends @NonNull T> other)

Return primary if it is non-null. If primary is null, invoke other and return the result of that invocation.

See Also:: Optional.orElseGet(Supplier)

orElseThrow

public static <T extends @NonNull java.lang.Object,X extends @NonNull java.lang.Throwable> T orElseThrow(T primary,
                                                                                                               java.util.function.Supplier<? extends X> exceptionSupplier)
                                                                                                        throws X extends @NonNull java.lang.Throwable

Return primary if it is non-null. If primary is null, throw an exception to be created by the provided supplier.

Throws:: X extends @NonNull java.lang.Throwable
See Also:: Optional.orElseThrow(Supplier)

Class Opt